Description:
An investigation was made of the change in the pressure limits of flame propagation with tube diameter for various isooctane-oxygen-nitrogen mixtures. Pressure limits were measured in cylindrical glass tubes of four different inside diameters at six different oxygen-nitrogen ratios. Under the experimental conditions, flame propagation was found to be impossible in isooctane-oxygen mixtures with oxygen concentrations less than 11 to 12 percent. Critical tube diameters for flame propagation were calculated and the effect of pressure was determined and compared with the effect of pressure on quenching distance. Critical diameters were related to flame speeds for various isooctane-oxygen-nitrogen mixtures.

Description:
Report presenting an experimental investigation to determine the combustion properties of aluminum as a fuel for use in high-speed aircraft. The aluminum fuel was injected both in powder and wire form into 2-inch-diameter ramjet-type combustors. Results regarding operational problems, thrust, and combustion efficiency are provided.

Description:
From Summary: "A rapidly convergent successive approximation process is described that simultaneously determines both composition and temperature resulting from a chemical reaction. This method is suitable for use with any set of reactants over the complete range of mixture ratios as long as the products of reaction are ideal gases. An approximate treatment of limited amounts of liquids and solids is also included. This method is particularly suited to problems having a large number of products of reaction and to problems that require determination of such properties as specific heat or velocity of sound of a dissociating mixture."

Description:
Report presenting an approximation process that can be used to determine both composition and temperature resulting from a chemical reaction. It is suitable for use with any set of reactants over the complete range of mixture ratios as long as the products of reaction are ideal gases.

Description:
Note presenting the results of a preliminary study of combustion in flowing gases and apparatus for obtaining high rates of heat release per unit volume of combustion space are described. Tests were made over a wide range of fuel-air ratios, inlet-mixture velocities, and electrical heat inputs, using propane gas as the fuel. Results indicate that the greater the surface-volume ratio, or the greater the amount of heat addible to the gas stream, the greater the inlet-mixture velocity at which appreciable combustion can be obtained.

Description:
Report presenting a system of general equations for computing the burning rates of small particles burning as diffusion flames. Two types of solutions are carried out: a complex numerical integration and a less complicated and rigorous analytical solution involving stepwise iteration across the temperature profile.

Description:
This paper discusses the thermal theory of combustion and explosion, and conditions of ignition: transformation accompanied by heat liberation, transformation rate and temperature dependence.

Description:
This paper attempts to state laws for the self-ignition and combustion of gases in a comprehensive manner. The primary focus is recent investigations in which new combustion phenomena or new methods of studying them experimentally are brought out and investigations that throw new light on already known phenomena.

Description:
Three low-pressure rocket motor propellant burn tests were performed in a large, sealed test chamber located at the X-tunnel complex on the Department of Energy's Nevada Test Site in the period May--June 1997. NIKE rocket motors containing double base propellant were used in two tests (two and four motors, respectively), and the third test used two improved HAWK rocket motors containing composite propellant. The preliminary containment safety calculations, the crack and burn procedures used in each test, and the results of various measurements made during and after each test are all summarized and collected in this document.

Description:
Propagation of a fire that originates in a single glovebox to other locations in the Plutonium Facility at Los Alamos National Laboratory is conceivable only if transport of hot combustion gases to other locations causes ignition of combustible materials elsewhere in the system (i.e., flashover). This paper describes a model developed, using the MELCOR computer code, to calculate the generation and transport of combustion gas mass and energy during postulated glovebox fire accident scenarios. The accident scenarios involved a wide spectrum of glovebox operating and potential fire conditions to determine whether flashover conditions could occur at locations outside the burning glovebox: o A variety of combustible material characteristics was considered (e.g., type, quantity, and combustion properties of combustible material). o A spectrum of safety system operating conditions was considered (e.g., glovebox ventilation system operating normally vs an inoperative exhaust fan; drop-box fir e damper closure vs failure to close). o A range of analytical modeling assumptions was considered (e.g., the extent to which heat transfer between hot combustion gases and the glovebox walls is represented in the model). Example results of these calculations are presented to illustrate the benefits obtained and lessons learned by using a computational tool like MELCOR for this analysis.

Description:
A dynamic model of a furnace flame is presented. The model simulates the preheat, combustion, and postcombustion regions of a wall-fired coal furnace. The set of nonlinear differential equations describing the flame dynamics are derived from the fundamental equations of conservation of mass and energy. The key approximations for flows across the moving boundary and spatial distribution functions for the carbon and oxygen concentrations in the combustion zone are developed. Sample results of transient calculations are presented.

Description:
We measure the Laminar burn rates of explosives at extreme conditions (up to 520K and 1 GPa) in a hybrid strand burner, to provide reaction rate data for prediction of violence of thermal response. Data from a series of HMX-based explosives show that explosives with high binder content (15 wt%) burn smoothly over the entire pressure range regardless of particle size, while explosives with less binder eventually transition to a rapid erratic burn 10-100 times faster. When heated to ~ 440K, an HMX formulation with fine particles and 15% binder exhibits different burning behav- ior depending on the details of the temperature-pressure history, apparently as a result of the {beta} {yields} {delta} phase transition in HMX. Burn rates can be increased by 1000-fold under certain conditions.

Description:
The objective of this project was to improve understanding and modeling of flashback, a significant issue in low emissions combustors containing high levels of hydrogen. Experimental studies were performed over a range of fuel compositions, flow velocities, reactant temperatures, and combustor pressures to study the factors leading to flashback. In addition, high speed imaging of the flashback phenomenon was obtained. One of the key conclusions of this study was that there existed multiple mechanisms which lead to flashback, each with different underlying parametric dependencies. Specifically, two mechanisms of 'flashback' were noted: rapid flashback into the premixer, presumably through the boundary layer, and movement of the static flame position upstream along the centerbody. The former and latter mechanisms were observed at high and low hydrogen concentrations. In the latter mechanism, flame temperature ratio, not flame speed, appeared to be the key parameter describing flashback tendencies. We suggested that this was due to an alteration of the vortex breakdown location by the adverse pressure gradient upstream of the flame, similar to the mechanism proposed by Sattelmayer and co-workers [1]. As such, a key conclusion here was that classical flashback scalings derived from, e.g., Bunsen flames, were not relevant for some parameter regimes found in swirling flames. In addition, it was found that in certain situations, pure H2 flames could not be stabilized, i.e., the flame would either flashback or blowout at ignition. This result could have significant implications on the development of future high hydrogen turbine systems.

Description:
Laboratory experiments were conducted at gas turbine and atmospheric conditions (0.101 &lt; P{sub 0} &lt; 0.810 MPa, 298 &lt; T{sub 0} &lt; 580K, 18 &lt; U{sub 0} &lt; 60 m/s) to characterize the overall behaviors and emissions of the turbulent premixed flames produced by a low-swirl injector (LSI) for gas turbines. The objective was to investigate the effects of hydrogen on the combustion processes for the adaptation to gas turbines in an IGCC power plant. The experiments at high pressures and temperatures showed that the LSI can operate with 100% H{sub 2} at up to {phi} = 0.5 and has a slightly higher flashback tolerance than an idealized high-swirl design. With increasing H{sub 2} fuel concentration, the lifted LSI flame begins to shift closer to the exit and eventually attaches to the nozzle rim and assumes a different shape at 100% H{sub 2}. The STP experiments show the same phenomena. The analysis of velocity data from PIV shows that the stabilization mechanism of the LSI remains unchanged up to 60% H{sub 2}. The change in the flame position with increasing H{sub 2} concentration is attributed to the increase in the turbulent flame speed. The NO{sub x} emissions show a log linear dependency on the adiabatic flame temperature and the concentrations are similar to those obtained previously in a LSI prototype developed for natural gas. These results show that the LSI exhibits the same overall behaviors at STP and at gas turbine conditions. Such insight will be useful for scaling the LSI to operate at IGCC conditions.

Description:
As a high explosive (HE) ages, those properties of the HE dependent on its global energy-release rate (e.g. shock initiation and detonation propagation speed) are the most likely to be affected. Similarly, any HE replacement will bring with it changes in these same reaction rate dependent characteristics of the HE, in that the new material will not be identical to that being replaced. In this paper the authors describe how detonation shock dynamics (DSD) theory can be used to model how changes in the energy-release rate (as they are embodied in the HE`s detonation speed vs curvature relation) influence the speed of detonation propagation and in turn the performance of a system.

Description:
The overall objective of the project was to develop a methodology to identify different type of particles in flames using light diagnostic techniques. During the course of this project, the authors completed a total of eight publications. A short summary of these eight papers is presented here along with the eighth paper. In this eighth study, a methodology is discussed to identify the Mueller (scattering) matrix elements of soot agglomerates in diffusion flames. For this purpose, an experimental system based on Nd:YAG laser and optical parametric oscillator is designed and built. The technique is first tested numerically for different size soot agglomerates and very good agreements were observed. After that, elliptically polarized laser light is directed on an ethylene diffusion flame. Scattered light from the flame is passed through a polarizer/retarder pair before being measured. By repeating this procedure for six different conditions, six important elements of the scattering matrix are measured. The comparison of the trends of experimental and numerical data shows that this method is very promising for flame studies.

Description:
Thermochemical pyrolysis of solid biomass feedstocks, with subsequent condensation of the pyrolysis vapors, has been investigated in the U.S. and internationally as a means of producing a liquid fuel for power production from biomass. This process produces a fuel with significantly different physical and chemical properties from traditional petroleum-based fuel oils. In addition to storage and handling difficulties with pyrolysis oils, concern exists over the ability to use this fuel effectively in different combustors. The report endeavors to place the results and conclusions from Sandia's research into the context of international efforts to utilize pyrolysis oils. As a special supplement to this report, Dr. Steven Gust, of Finland's Neste Oy, has provided a brief assessment of pyrolysis oil combustion research efforts and commercialization prospects in Europe.

Description:
AMAX Coal Company (AMAX) has built a 200 tph, demonstration scale fluidized-bed drying process at their Belle Ayr Mine in Wyoming to dry the subbituminous coal of Wyodak seam from an average moisture content of 25-30 wt% to about 10 wt%. Currently, the dryer generates too many fines for proper transportation and handling. Though the raw coal is about 2-inch top size, about 80 wt% of the dryer product ends up finer than 28 mesh, and about 10 wt% of the dried coal is collected in the dryer bag house (minus 200 mesh). Paul Woessner, Director of Research and Development of AMAX, met with personnel from PETC Coal Preparation Division and expressed an interest in an investigation of the feasibility of applying the PETC`s humic acid binder to reconstitute the bag house fines from the dryer. This was an area in which PETC had been doing some research and had some expertise. As a result, AMAX and the U.S. Department of Energy`s Pittsburgh Energy Technology Center (PETC) signed a Cooperative Research and Development Agreement (CRADA, see appendix A) in June 1990 to produce, from fine subbituminous coal, economic low moisture reconstituted solid fuel forms that have suitable storage, handling, transportation, and combustion properties. PETC`s task in this agreement was to conduct broad, baseline studies in three areas: (1) to develop a humic acid binder from AMAX subbituminous coal using the PETC-developed Humic Acid Binder Process, (2) to reconstitute AMAX`s dried subbituminous coal fines from the bag house and the fluidized bed dryer product with humic acid binder, and (3) to produce low moisture, water-resistant pellets from raw subbituminous coal by the PETC-developed Lignipel Process. AMAX, on the other hand, agreed to produce 1-2 tons of reconstituted solid fuel for handleability and combustion tests and partially funded PETC`s efforts.

Description:
The main goal of this research project is to evaluate the combustion characteristics of the slurry fuels prepared from the recovered coal fines and plant coal fines. A specific study was completed which collected data on combustion behavior, flame stability, ash behavior and emission of SO{sub 2} NO{sub x} and particulate in a well insulated laboratory scale furnace in which the residence time and temperature history of the burning particles are similar to that of utility boiler furnace at 834,330 Btu/hr input and an average of 15% excess air. The slurry fuel was prepared at 53.5% solid to match the generic slurry properties. The coal blend was prepared using a mix of 15% wet milled pond fines and 85% plant fines. Combustion characteristics of the slurry fuels were determined at three different firing rates: 834,330 Btu/hr, 669,488 Btu/hr and 508,215 Btu/hr. Finally a comparison of the results is being developed to determine the advantages of coal water slurry fuel over the plant coal blended form.

Description:
The main goal of this research project is to evaluate the combustion characteristics of the slurry fuels prepared from the recovered coal fines and plant coal fines. A specific study was completed which collected data on combustion behavior, flame stability, ash behavior, emissions of SO{sub 2} and NO{sub x}, and particulate in a well insulated laboratory scale furnace. In addition, the residence time and temperature history of the burning particles are similar to that of utility boiler furnace at 834,330 Btu/hr input at an average of 15% excess air. The slurry fuel was prepared at 53.5% solid to match the generic slurry properties. The coal blend was prepared using a mixture of 15% wet milled pond fines and 85% plant fines. Combustion characteristics of the slurry fuels were determined at three different firing rates: 834,330 Btu/hr, 669,488 Btu/hr, and 508,215 Btu/hr. Finally, a comparison of the results will be developed for determining the advantages of coal-water slurry fuel over the plant coal blend form.

Description:
A coal-water slurry fuel (CWSF) program is being undertaken to determine if CWSFs prepared from cleaned coal (containing approximately 3.5 wt.% ash and 0.9 wt.% sulfur) can be burned effectively in a heavy fuel oil-designed industrial boiler without adverse impact on boiler rating, maintainability, reliability, and availability. Information will also be generated to help in the design of new systems specifically configured to fire these clean coal-based fuels. The project consists of four phases: (1) design, permitting, and test planning, (2) construction and start up, (3) demonstration and evaluation (1,000-hour demonstration), and (4) expanded demonstration and evaluation (installing a CWSF preparation circuit, conducting an additional 1,000 hours of testing, and installing an advanced flue gas treatment system). The boiler testing and evaluation will determine if the CWSF combustion characteristics, heat release rate, fouling and slagging behavior, corrosion and erosion tendencies, and fuel transport, storage, and handling characteristics can be accommodated In a boiler system designed to fire heavy fuel oil. In addition, the proof-of-concept demonstration will generate data to determine how the properties of a CWSF and its parent coal affect boiler performance. The economic factors associated with retrofitting boilers will also be evaluated. The first three phases have been completed and the combustion performance of the burner that was provided with the boiler did not meet performance goals. A maximum coal combustion efficiency of 95% (target is 98%) was achieved; however, natural gas cofiring was necessary to maintain a stable flame. Consequently, the first demonstration was terminated after 500 hours. The second demonstration (Phase 4) will be conducted after a proven CWSF-designed burner is installed on the boiler. Prior to starting the second demonstration, a CWSF preparation circuit was constructed to provide flexibility in CWSF production.

Description:
Methods of producing non-sooting, low flame temperature diesel combustion were investigated in an optically-accessible, quiescent constant-volume combustion vessel under mixing-controlled diesel combustion conditions. Combustion and soot processes of single, isolated fuel jets were studied after auto-ignition and transient premixed combustion and while the injector was fully-open (i.e. during the mixing-controlled phase of heat release for diesel combustion). The investigation showed that small injector tip orifices could be used to produce non-sooting and low flame temperature combustion simultaneously. The use of small orifices was shown to enable non-sooting and low flame temperature combustion in two different ways as summarized below. A more detailed description of the experimental methods and results is provided in Ref. [1-3]. First, using an injector tip with a 50 micron orifice and ambient oxygen concentrations as low as 10% (simulating the use of extensive EGR), a fuel jet was non-sooting at typical diesel ambient temperatures (1000 K). Second, using the same injector tip at a reduced ambient gas temperature (850 K), but with 21% oxygen, it was shown that non-sooting, mixing-controlled combustion occurred at the lift-off length in a fuel-air mixture with a cross-sectional average equivalence ratio of approximately 0.6-suggesting that the quasi-steady combustion was fuel-lean and thereby avoided the formation of a diffusion flame. The adiabatic flame temperature with reduced ambient oxygen concentration or fuel-lean combustion was approximately 2000 K, compared to typical diesel flame temperatures that exceed 2600 K. The 50 micron orifice results above were obtained using a No.2 diesel fuel. However, using an oxygenated fuel (20 wt% oxygen), the investigation showed that the same low temperature combustion, either with reduced ambient oxygen concentration or fuel-lean combustion, was realized with a 100 micron orifice. Although these single, isolated jets do not have jet-jet interactions that would occur in realistic engines, the results are useful ...

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